Edit: Never mind, I guess you weren't trying to explain that part. The wording is just a bit odd though, in terms of, we haven't proven that $\displaystyle a^n-1$ is prime, merely stating conditions for it being possible.

Edit: Never mind, I guess you weren't trying to explain that part. The wording is just a bit odd though, in terms of, we haven't proven that $\displaystyle a^n-1$ is prime, merely stating conditions for it being possible.